Help me buy new trainers please!

[LazyDoll]

Today 13:02 LazyDoll

Hi,
I tried this first in excercise but thought I'd post over here too!
My second pair of Asics are due to be replaced and my exercise routine has changed a fair bit so I'm not sure if I could make do with 'cheaper' trainers now or not?!
I used to run up to 30km a week so needed a lot of support/cushioning.
I've since mixed up my exercise routine to include bootcamp, running but 5-8km max runs and mountain biking.
Have been looking at karrimor which are a fraction of the price but wondering if I get them will I just end up spending twice and should just bite the bullet and stick with what I'm used too!?
Help please!!